Shoulder prosthesis

Abstract

A prosthesis may include a stem, a ball stud, an adaptor, and a head. The stem may include a longitudinal axis and a bore having a central axis that is angled relative to the longitudinal axis. The ball stud may include a cylindrical shaft and a ball end. The cylindrical shaft may be received in the bore of the stem. The adaptor may include a tapered outer surface and a ball socket rotatably receiving the ball end of the stud. The head may be rotatably supported by the adaptor and may include a semispherical articulating surface and a female taper rotatably receiving the tapered outer surface of the adaptor.

What is claimed is: 
     
       1. A joint prosthesis comprising:
 a stem having a stem longitudinal axis and a stem bore formed in a proximal face of the stem at an angle to the stem longitudinal axis; 
 an adaptor including:
 a ball stud having a spherical section and a shank extending from the spherical section, the shank configured for insertion within the stem bore, the spherical section including a divided ball segment, 
 an adaptor body having a central adaptor body axis and defining a cavity sized and shaped to receive the spherical section of the ball stud, the cavity having a central cavity axis that is offset from the central adaptor body axis, and 
 a fastener configured to be at least partially received within a bore of the ball stud, the fastener including a screw portion and a wedge portion; and 
 
 a head having a central head axis and defining a depression sized and shaped to receive the adaptor body, the head configured to be coupled to the adaptor body such that the central adaptor body axis is offset from the central head axis; 
 wherein the head is adjustably positionable relative to the stem through rotation of the spherical section of the ball stud relative to the cavity of the adaptor body to set at least one of an angular inclination and version of the head with respect to the stem, and through rotation of the adaptor body relative to the head to set a radial offset of the head with respect to the stem; and 
 wherein as the screw portion is driven into the wedge portion during assembly, the wedge portion expands within the cavity thereby fixedly securing the adaptor body and the ball stud in a fixed relationship. 
 
     
     
       2. The joint prosthesis of  claim 1 , wherein the adaptor includes a plurality of indicia for indicating a degree of adjustment of the radial offset. 
     
     
       3. The joint prosthesis of  claim 1 , wherein the head includes a plurality of indicia for indicating alignment of the radial offset. 
     
     
       4. The joint prosthesis of  claim 1 , wherein the adaptor body has a male taper and the depression has a complementary female taper. 
     
     
       5. The joint prosthesis of  claim 1 , wherein the joint prosthesis is a shoulder prosthesis. 
     
     
       6. A joint prosthesis comprising:
 a stem having a longitudinal axis and a proximal face defining a stem bore, the stem configured to be inserted into a first bone; 
 a head configured to articulate with a second bone or an implant component attached to the second bone, the head defining a head taper; 
 an adaptor comprising a ring and a ball stud having a shank segment sized to be received in the stem bore, the ring defining an attachment aperture and having a tapered outer surface for securing the ring to the head via the head taper, the attachment aperture sized to receive the ball stud in a fixed orientation; and 
 a plurality of indicia, including at least one indicator on the adaptor and a plurality of indicators on the head; 
 wherein the head is positionable relative to the stem through rotation of the head about the adaptor for adjusting at least one of an angular inclination and a radial offset of the head, and 
 wherein the indicia are configured for indicating a degree of adjustment of the at least one of the angular inclination and the radial offset; and a fastener configured to be at least partially received within a bore of the ball stud, the fastener including a screw portion and a wedge portion, wherein as the screw portion is driven into the wedge portion during assembly, the wedge portion expands within the attachment aperture thereby fixedly securing the ring and the ball stud in the fixed orientation. 
 
     
     
       7. The joint prosthesis of  claim 6 , wherein when in an assembled state, an axis of rotation of the ball stud and a central axis of the ring are eccentric. 
     
     
       8. The joint prosthesis of  claim 6 , wherein when in an assembled state, a central axis of the stem bore and an axis of rotation of the ball stud are concentric. 
     
     
       9. The joint prosthesis of  claim 6 , wherein when in an assembled state, a central axis of the head and a central axis of the ring are eccentric. 
     
     
       10. The joint prosthesis of  claim 6 , wherein the joint prosthesis is a shoulder prosthesis. 
     
     
       11. A joint prosthesis comprising:
 a stem configured to be implanted in a first bone and defining a stem bore; 
 a head having an articulation surface and an end surface defining a depression, the articulation surface configured to articulate with a second bone or an implant component connected to the second bone; 
 an adaptor sized to be received in the depression and form a taper connection between the adaptor and the head, the adaptor further defining an aperture; 
 a ball stud having a first end and a second end, the first end sized to be received in the aperture, the second end sized to be received in the stem bore; and 
 a plurality of indicia, including a plurality of indicators on the adaptor and a plurality of indicators on the head; 
 wherein the first end of the ball stud includes a spherical surface, 
 wherein, when implanted, the head is positioned relative to the adaptor to define a radial offset of the head with respect to the adaptor, and the spherical surface of the ball stud is rotatable within the aperture to set an inclination angle of the head with respect to the stem, and 
 wherein the indicia are configured for indicating a degree of adjustment of one or both of the radial offset and the inclination angle; and a fastener configured to be at least partially received within a bore of the ball stud, the fastener including a screw portion and a wedge portion, wherein as the screw portion is driven into the wedge portion during assembly, the wedge portion expands within the aperture thereby fixedly securing the adaptor and the ball stud in a fixed orientation. 
 
     
     
       12. The joint prosthesis of  claim 11 , wherein the spherical surface of the ball stud allows for adjustment of an angle formed between a central axis of the head and a central axis of a shank segment extending from the spherical surface of the ball stud. 
     
     
       13. The joint prosthesis of  claim 11 , wherein the aperture of the adaptor is offset with respect to a central axis of the adaptor, the adaptor having a cylindrical outer surface and the depression having an inner surface that is shaped complementary with the cylindrical outer surface such that the adaptor can be rotated in the depression to set the radial offset of the head with respect to the adaptor. 
     
     
       14. The joint prosthesis of  claim 11 , wherein the first bone is a humerus, and the second bone is a scapula. 
     
     
       15. The joint prosthesis of  claim 11 , wherein when in an assembled state, an axis of rotation of the ball stud and a central axis of the adaptor are eccentric.